The Internet Protocol (IP) is the principal communications protocol used for relaying datagrams (also known as network packets) across an internetwork using the Internet Protocol Suite. Responsible for routing packets across network boundaries, it is the primary protocol that establishes the Internet.
IP is the primary protocol in the Internet Layer of the Internet Protocol Suite and has the task of delivering datagrams from the source host to the destination host solely based on the addresses. For this purpose, IP defines datagram structures that encapsulate the data to be delivered. It also defines addressing methods that are used to label the datagram source and destination.
The first major version of IP, Internet Protocol Version 4 (IPv4), is the dominant protocol of the internet. Internet Protocol version 4 (IPv4) is the fourth revision in the development of the Internet Protocol (IP) and the first version of the protocol to be widely deployed. Together with IPv6, it is at the core of standards-based internetworking methods of the Internet. As of 2012 IPv4 is still the most widely deployed Internet Layer protocol.
IPv4 is a connectionless protocol for use on packet-switched Link Layer networks (e.g., Ethernet). It operates on a best effort delivery model, in that it does not guarantee delivery, nor does it assure proper sequencing or avoidance of duplicate delivery. IPv4 uses 32-bit (four-byte) addresses, which limits the address space to 4,294,967,296 (232) addresses. Addresses were assigned to users, and the number of unassigned addresses decreased. IPv4 address exhaustion from Internet Assigned Numbers Authority occurred on Feb. 3, 2011. It had been significantly delayed by address changes such as classful network design, Classless Inter-Domain Routing, and network address translation (NAT). This limitation of IPv4 stimulated the development of IPv6 in the 1990s, which has been in commercial deployment since 2006.
IPv4 reserves special address blocks for private networks (˜18 million addresses) and multicast addresses (˜270 million addresses). IPv4 addresses may be written in any notation expressing a 32-bit integer value, but for human convenience, they are most often written in the dot-decimal notation, which consists of four octets of the address expressed individually in decimal and separated by periods (for example, 192.168.1.1).
The Internet operates by transferring data between hosts in packets that are routed across networks as specified by routing protocols. These packets require an addressing scheme, such as IPv4 or IPv6, to specify their source and destination addresses. Each host, computer or other device on the Internet requires an IP address in order to communicate. The growth of the Internet has created a need for more addresses than are possible with IPv4.
IPv6 was developed by the Internet Engineering Task Force (IETF) to deal with this long-anticipated IPv4 address exhaustion, and is described in Internet standard document RFC 2460, published in December 1998. Like IPv4, IPv6 is an internet-layer protocol for packet-switched internetworking and provides end-to-end datagram transmission across multiple IP networks. While IPv4 allows 32 bits for an IP address, and therefore has 232 (4,294,967,296) possible addresses, IPv6 uses 128-bit addresses, for an address space of 2128 (approximately 3.4×1038) addresses. This expansion allows for many more devices and users on the internet as well as extra flexibility in allocating addresses and efficiency for routing traffic. It also eliminates the primary need for network address translation (NAT), which gained widespread deployment as an effort to alleviate IPv4 address exhaustion. There are heretofore unaddressed needs with previous solutions in mapping users to IPV6 addresses.